Solar Impulse, the solar airplane that was set to fly across the United States, has taken off and completed the first leg of the journey from California to Arizona. Averaging an altitude of just 10,000 feet and a speed of 40.6 miles per hour, the flight took most of a day to complete. Technically, 14,000 people were on board, albeit virtually via streaming video.

Launching the “Clean Generation” initiative by completing the first leg of their 2013 Across America mission, Pilot Bertrand Piccard took off from Moffett Airfield at NASA’s Ames Research Center early Saturday morning, arriving at Phoenix’s Sky Harbor International Airport 18 hours and 18 minutes later.

Promoting greater investment in technologies for sustainable energy production and use, Piccard and Solar Impulse co-founder André Borschberg will alternate flying the five legs of the trip.”We’ve been dreaming about crossing the United States for years – the land of scientific research, innovation and aviation pioneers – and it’s hard to believe it’s really happening.” said Borschberg and Piccard as they walked down the runway in Phoenix.

Coming up in mid-May, the second leg of the journey will fly from Phoenix to Dallas/Fort Worth before continuing on to St Louis then Washington, D.C., before completing the first crossing of the United States by a solar-powered airplane at New York’s JFK airport.